Symbol too long for allsyms warnings on KSYM_NAME_LEN

[Arnd Bergmann]

My randconfig builds sometimes (around one in every 700 configs) run
into this warning on x86:

Symbol __pfx_snnnng1h2i3j4k5l6m7ng1h2i3j4k5l6m7nng1h2i3j4k5l6m7ng1h2i3j4k5l6m7nnng1h2i3j4k5l6m7ng1h2i3j4k5l6m7nng1h2i3j4k5l6m7ng1h2i3j4k5l6m7nnnng1h2i3j4k5l6m7ng1h2i3j4k5l6m7nng1h2i3j4k5l6m7ng1h2i3j4k5l6m7nnng1h2i3j4k5l6m7ng1h2i3j4k5l6m7nng1h2i3j4k5l6m7ng1h2i3j4k5l6m7nnnnng1h2i3j4k5l6m7ng1h2i3j4k5l6m7nng1h2i3j4k5l6m7ng1h2i3j4k5l6m7nnng1h2i3j4k5l6m7ng1h2i3j4k5l6m7nng1h2i3j4k5l6m7ng1h2i3j4k5l6m7nnnng1h2i3j4k5l6m7ng1h2i3j4k5l6m7nng1h2i3j4k5l6m7ng1h2i3j4k5l6m7nnng1h2i3j4k5l6m7ng1h2i3j4k5l6m7nng1h2i3j4k5l6m7ng1h2i3j4k5l6m7n too long for kallsyms (517 >= 512).
Please increase KSYM_NAME_LEN both in kernel and kallsyms.c

The check that gets triggered was added in commit c104c16073b
("Kunit to check the longest symbol length"), see
https://lore.kernel.org/all/20241117195923.222145-1-sergio.collado@xxxxxxxxx/

and the overlong identifier seems to be the result of objtool adding
the six-byte "__pfx_" string to a symbol in elf_create_prefix_symbol()
when CONFIG_FUNCTION_PADDING_CFI is set.

I think the suggestion to "Please increase KSYM_NAME_LEN both in
kernel and kallsyms.c" is misleading here and should probably be
changed. I don't know if this something that objtool should work
around, or something that needs to be adapted in the test.

      Arnd